A.1
Accuracy calculations
The information shows how to calculate accuracy for volts,
amps, ohms and coulombs.
A.1.1 Calculating volts accuracy
From the specifications, Volts is calculated as follows:
Accuracy = ±(% rdg + counts)
The following example shows how to compute accuracy for
the 2V range:
Assume that the voltage you are measuring is reading exactly
1.00000V on the 2V range.
From the specs:
Accuracy = ±(0.025% of 1V + 4 counts)
= ±(0. 4 counts)
= ±(0. 0.00004V)
= ±0.00029V
Note: 4 counts on the 2V range equals 0.00004 V
Thus, the accuracy range for the 1.00000V reading is
0.99971V to 1.00029V.
A.1.2 Calculating amps accuracy
From the specifications, Amps is calculated as follows:
Accuracy = ±(% rdg + counts)
The following example shows how to compute accuracy for
the 20mA range:
Assume that the current you are measuring is reading exactly
10.0000mA on the 20mA range.
From the specs:
Accuracy = ±(0.1% of 10mA + 5 counts)
= ±(0.01mA + 5 counts)
= ±(0.01mA + 0.0005mA)
= ±0.0105mA
Note: 5 counts on the 20mA range equals 00.0005mA
Thus, the accuracy range for the 10.0000mA reading is
9.9895mA to 10.0105mA.
A.1.3 Calculating ohms accuracy
The following information shows how to calculate ohms ac-
curacy for both Auto V-Source Ohms and Manual V-Source
Ohms.
Auto V-Source ohms
From the specifications, Auto V-Source Ohms accuracy is
calculated as follows:
Accuracy = ±(% rdg + counts)
The following example shows how to compute Auto V-
Source Ohms accuracy for the 2M
Ω
range:
Assume that the resistor you are measuring is reading exactly
1.00000M
Ω
on the 2M
Ω
range.
From the specs:
Accuracy = ±(0.125% of 1M
Ω
+ 1 count)
= ±(1250
Ω
+ 1 count)
= ±(1250
Ω
+ 10
Ω
)
= ±1260
Ω
Note: 1 count on the 2M
Ω
range (0.00001M
Ω
) equals
10
Ω
Thus, the accuracy range for the 1.00000M
Ω
Auto V-Source
reading is 0.99874M
Ω
to 1.00126M
Ω
.
Manual V-Source ohms
Accuracy for Manual V-Source Ohms is determined by cal-
culating the accuracy of the amps measurement and the ac-
curacy of the V-Source. Accuracy for ohms is then calculated
(R = V/I) using the worst case amps and volts readings.
The following example shows how to compute Manual V-
Source Ohms accuracy:
Assume that the test voltage is set for 100.000V, AUTO mea-
surement range is enabled, and the resistor you are measur-
ing is reading exactly 01.0000M
Ω
. Also assume that the
amps reading is 1.000e-04 A (100.000µA) on the 200µA
range. This reading is available as a multiple (NEXT) display
(MEAS and SRC).
Amps accuracy for the 100µA reading (200µA range) is cal-
culated as follows:
Accuracy = ±(% rdg + counts)
= ±(0.1% of 100µA + 5 counts)
= ±(0.1µA + 5 counts)
= ±(0.1µA + 0.005µA)
= ±(0.105µA)
Specifications A-5
